This word indeed is not a Spanish word. Although made popular by Joe Arroyo in Colombia in the early 80's, this song is not originally by him. The original song dates from the mid 70's and is by an Aruban artist named Robert Jeandor.
The original song is in Papiamento which is the native language in the islands of Aruba, Curacao and Bonaire. The lyrics were adapted by Arroyo to Spanish but the word "Bolobonchi" could not be adapted to Spanish since there is nothing equivalent in the Spanish vocabulary. "Bolobonchi" literally means a "goose egg" (that one gets by bumping one's head).
The song is also not a Salsa but a Tumba, which is an African rhythm used during the Carnival season in the ABC Islands.
The following is a soundcloud link to a more recent rendition by the original artist in the original language.